From 78004e9a87f240df03e2f73120d291763c32e0a7 Mon Sep 17 00:00:00 2001 From: Ali Ahmet Memis Date: Fri, 21 Aug 2026 01:45:27 +0000 Subject: openrisc: fix arbitrary kernel memory access via or1k_atomic syscall sys_or1k_atomic() (syscall 244 in the "or1k" ABI) takes two user pointers, v1 and v2, and swaps the words they point to in hand-written assembly. l.lwz r29,0(r4) l.lwz r27,0(r5) l.sw 0(r4),r27 l.sw 0(r5),r29 The pointers are not checked with access_ok(). The four memory accesses also have no exception table entries. A caller passes a kernel address as either pointer, and the syscall reads from and writes to it directly. This gives an unprivileged process a kernel read/write primitive. It overwrites kernel data such as the sys_call_table, gaining code execution in kernel context. Check both pointers before entering the critical section. Add fixups for the four memory accesses so faults on valid but unmapped user addresses return -EFAULT. [shorne@gmail.com: fix comment style] Fixes: 9d02a4283e9c ("OpenRISC: Boot code") Cc: stable@vger.kernel.org Signed-off-by: Ali Ahmet Memis Signed-off-by: Stafford Horne --- arch/arm/lib/memcpy.S | 66 +++++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 66 insertions(+) create mode 100644 arch/arm/lib/memcpy.S (limited to 'arch/arm/lib/memcpy.S') diff --git a/arch/arm/lib/memcpy.S b/arch/arm/lib/memcpy.S new file mode 100644 index 000000000..90f2b645a --- /dev/null +++ b/arch/arm/lib/memcpy.S @@ -0,0 +1,66 @@ +/* SPDX-License-Identifier: GPL-2.0-only */ +/* + * linux/arch/arm/lib/memcpy.S + * + * Author: Nicolas Pitre + * Created: Sep 28, 2005 + * Copyright: MontaVista Software, Inc. + */ + +#include +#include +#include + +#define LDR1W_SHIFT 0 +#define STR1W_SHIFT 0 + + .macro ldr1w ptr reg abort + W(ldr) \reg, [\ptr], #4 + .endm + + .macro ldr4w ptr reg1 reg2 reg3 reg4 abort + ldmia \ptr!, {\reg1, \reg2, \reg3, \reg4} + .endm + + .macro ldr8w ptr reg1 reg2 reg3 reg4 reg5 reg6 reg7 reg8 abort + ldmia \ptr!, {\reg1, \reg2, \reg3, \reg4, \reg5, \reg6, \reg7, \reg8} + .endm + + .macro ldr1b ptr reg cond=al abort + ldrb\cond \reg, [\ptr], #1 + .endm + + .macro str1w ptr reg abort + W(str) \reg, [\ptr], #4 + .endm + + .macro str8w ptr reg1 reg2 reg3 reg4 reg5 reg6 reg7 reg8 abort + stmia \ptr!, {\reg1, \reg2, \reg3, \reg4, \reg5, \reg6, \reg7, \reg8} + .endm + + .macro str1b ptr reg cond=al abort + strb\cond \reg, [\ptr], #1 + .endm + + .macro enter regs:vararg +UNWIND( .save {r0, \regs} ) + stmdb sp!, {r0, \regs} + .endm + + .macro exit regs:vararg + ldmfd sp!, {r0, \regs} + .endm + + .text + +/* Prototype: void *memcpy(void *dest, const void *src, size_t n); */ + +ENTRY(__memcpy) +ENTRY(mmiocpy) +WEAK(memcpy) + +#include "copy_template.S" + +ENDPROC(memcpy) +ENDPROC(mmiocpy) +ENDPROC(__memcpy) -- cgit v1.3.1